Continued investigation is planned of the pathogenesis of corneal and trigeminal ganglion infection after corneal inoculation of thymidine kinase negative (TK-) mutants of herpes simplex virus (HSV). In this way study of the role of HSV TK expression in latent trigeminal ganglion neuronal infection will be determined. Results of initial studies have indicated the importance of viral TK expression. Replication of HSV TK-mutants in peripheral nonneuronal tissues will also be studied. We will also continue to utilize the ultracentrifugal inoculation technique to study low levels of infectious HSV. Conditions of the ultracentrifugation in cell culture studies willbe investigated to determine optimum conditions. In addition, we will further study ultracentrifugal inoculation of cell-free homogenates of latently infected trigeminal ganglia to detect infectious virus. If infectious virus is detected this will be evdence of a productive type of latent infection.